## captures the listed variables in the map
function(map_capture map )
  set(__map_capture_args ${ARGN})
  list_extract_flag(__map_capture_args --reassign)
  ans(__reassign)
  list_extract_flag(__map_capture_args --notnull)
  ans(__not_null)
  foreach(__map_capture_arg ${__map_capture_args})
    
    if(__reassign AND "${__map_capture_arg}" MATCHES "(.+)[:=](.+)")
      set(__map_capture_arg_key ${CMAKE_MATCH_1})
      set(__map_capture_arg ${CMAKE_MATCH_2})
    else()
      set(__map_capture_arg_key "${__map_capture_arg}")
    endif()
   # print_vars(__map_capture_arg __map_capture_arg_key)
    if(NOT __not_null OR NOT "${${__map_capture_arg}}_" STREQUAL "_")
      map_set(${map} "${__map_capture_arg_key}" "${${__map_capture_arg}}")
    endif()
  endforeach()
endfunction()

